Enzymes are used commercially to extract juice from apples. You will investigate the effect of an enzyme on the extraction of apple juice. You are provided with - apple pulp in a container, labelled W1 . - $5\text{ cm}^3$ of 2% enzyme solution in a test-tube, labelled '2% enzyme' . - $5\text{ cm}^3$ of water in a test-tube labelled 'no enzyme' . - two small containers. Proceed as follows: - Label the two small containers, A and B . - Using a plastic spoon divide the apple…

Biology 5090/31 — October/November 2012

Cambridge O-Level · Practical Test · worked solutions for every part, with the mark scheme

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marks

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Topics Experimental Contexts · Observations and Measurements · Planning Experiments and Investigations · Analysis, Conclusions and Evaluation · Microscopy and Biological Drawing · Use of Techniques, Apparatus and Materials

Q116MPlanning Experiments and InvestigationsObservations and MeasurementsAnalysis, Conclusions and EvaluationExperimental ContextsFree sample

Enzymes are used commercially to extract juice from apples.

You will investigate the effect of an enzyme on the extraction of apple juice.

You are provided with

apple pulp in a container, labelled W1.
$5\text{ cm}^3$ of 2% enzyme solution in a test-tube, labelled '2% enzyme'.
$5\text{ cm}^3$ of water in a test-tube labelled 'no enzyme'.
two small containers.

Proceed as follows:

Label the two small containers, A and B.
Using a plastic spoon divide the apple pulp equally into the two containers.
Take the container of apple pulp, labelled A, add the contents of the test-tube labelled '2% enzyme'. Stir the mixture carefully with a plastic spoon.
Remove, wash and wipe the spoon before using it again.
To the container of apple pulp, labelled B, add the contents of the test-tube labelled 'no enzyme'. Stir the mixture carefully with the plastic spoon.

Record the time when you have completed this.

time = ______

Allow the two containers A and B to stand for 10 minutes to allow the enzyme to react.

Use the 10 minutes to read through the following instructions you will be carrying out and answer (a).

Stage 1 After the 10 minutes, filter each of the mixtures found in containers A and B, using the two sets of apparatus provided, as shown in Fig. 1.1.

Fig. 1.1

Stage 2 Allow the juice to filter from each mixture for 12 minutes.

Use this 12 minutes to answer (c) and (d)

Stage 3 Record the appearance of juice from each container, A and B, in your table.

Stage 4 Measure the volume of juice collected from each mixture. Record the volumes in your table.

(a)

Construct a table to record the appearance and volume of juice collected from each mixture.

(b)

With reference to your results, compare the volume and appearance of the two juices extracted.

(c)

Explain why the following procedures were carried out.

(i)

washing the plastic spoon

(ii)

stirring the mixtures

(iii)

adding $5\text{ cm}^3$ of water in the test-tube labelled 'no enzyme'.

(d)

Some students carried out a similar investigation to find the effect of pH on the production of apple juice using this enzyme.

Fig. 1.2 shows a graph of their results.

Fig. 1.2

(i)

State the optimum pH for the action of this enzyme.

______

(ii)

Describe and explain the effect of pH on the production of apple juice, using this enzyme.

Return to the instructions for stages 3 and 4, complete (a) and (b).

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2 more questions

Q2Microscopy and Biological Drawing · Experimental Contexts · Observations and Measurements17M
Q3Experimental Contexts · Use of Techniques, Apparatus and Materials7M

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